Your network contains an Active Directory forest.
The forest contains two domains named contoso.com and fabrikam.com.
The forest functional level is Windows 2000. The contoso.com domain contains domain controllers that run either Windows Server 2008 or Windows Server 2008
R2.
The domain functional level is Windows Server 2008.
The fabrikam.com domain contains domain controllers that run either Windows 2000 Server or Windows Server 2003.
The domain functional level is Windows 2000 native.
The contoso.com domain contains a member server named Server1 that runs Windows Server 2012 R2.
You need to add Server1 as a new domain controller in the contoso.com domain.
What should you do first?

A.
Raise the functional level of the contoso.com domain to Windows Server 2008 R2.

B.
Upgrade the domain controllers that run Windows Server 2008 to Windows Server 2008 R2.

C.
Raise the functional level of the fabrikam.com domain to Windows Server 2003.

D.
Decommission the domain controllers that run Windows 2000.

E.
Raise the forest functional level to Windows Server 2003.

Explanation:
D)
Server 2003 is the minimum Domain Functional level for any domain in the forest Windows Server 2012 R2 requires a Windows Server 2003 forest functional
level.
That is, before you can add a domain controller that runs Windows Server 2012 R2 to an existing Active Directory forest, the forest functional level must be
Windows Server 2003 or higher.
http://technet.microsoft.com/en-us/library/cc771294.aspx